Microparticle sorting device, microparticle sorting system, droplet sorting device, droplet control device, and droplet control program

ABSTRACT

To provide a droplet forming technology capable of stably sorting a droplet.Provided is a microparticle sorting device provided with a voltage supply unit that supplies a drive voltage to a vibration element that applies a vibration to an orifice that generates a fluid stream, a control unit that controls a driving condition supplied to the vibration element on the basis of a relative relationship between a droplet discharged from the orifice and a satellite droplet present between droplets, and a sorting unit that sorts the droplet containing microparticles on the basis of optical information detected from the microparticles flowing through a flow path.

TECHNICAL FIELD

The present technology relates to a microparticle sorting device, amicroparticle sorting system, a droplet sorting device, a dropletcontrol device, and a droplet control program. More specifically, thisrelates to a technology of sorting and recovering a droplet containingspecific particles and the like.

BACKGROUND ART

An optical measurement method using flow cytometry (flow cytometer) isconventionally used for analyzing bio-related microparticles such ascells, microorganisms, and liposomes. The flow cytometer is a devicethat irradiates particles flowing through a flow path formed in a flowcell, a microchip and the like with light, and detects fluorescence orscattered light emitted from each particle to analyze.

Some flow cytometers have a function of sorting to recover onlyparticles having specific characteristics on the basis of an analysisresult, and a device that especially sorts the cells is called as a“cell sorter”. In the cell sorter, in general, a vibration element andthe like applies a vibration to the flow cell or microchip to make fluiddischarged from the flow path thereof droplets (refer to PatentDocuments 1 and 2). The droplet separated from the fluid is charged witha positive (+) or negative (−) charge, then a travel direction thereofis changed by a deflection plate and the like, and the droplet isrecovered in a predetermined container and the like.

In contrast, a device such as the cell sorter that sorts the droplettends to have unstable sorting performance due to an effect and the likeof temperature change, hydraulic pressure fluctuation, and differentialpressure due to change in sheath pressure. Therefore, in order tostabilize the sorting performance, a microparticle sorting device thatcontrols a drive voltage of a voltage supply unit by imaging the fluidand droplet discharged from an orifice of the flow cell or microchip anddetecting the droplet from the image is conventionally proposed (referto Patent Document 3).

Furthermore, Patent Document 4 discloses a technology of stably forminga droplet by providing, on a droplet sorting device, a detection unitthat detects a state of a droplet discharged from an orifice thatgenerates a fluid stream and a satellite droplet present between thedroplets, and a control unit that controls a frequency of a drivevoltage supplied to a vibration element that applies a vibration to theorifice on the basis of a position in which the satellite droplet ispresent.

CITATION LIST Patent Document

Patent Document 1: Japanese Unexamined Patent Publication

Patent Document 2: Japanese Patent Application Laid-Open No. 2010-190680

Patent Document 3: International Publication No. 2013/145905

Patent Document 4: Japanese Patent Application Laid-Open No. 2016-57286

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Although a sorting performance in a microparticle sorting technology isimproved day by day by the above-described conventional technology, itis also a fact that a droplet forming technology that is lesssusceptible to environmental fluctuation such as temperature change andhas excellent robustness is expected.

Therefore, a principal object of the present technology is to provide adroplet forming technology capable of stably sorting a droplet.

Solutions to Problems

First, the present technology provides a microparticle sorting deviceprovided with

-   -   a voltage supply unit that supplies a drive voltage to a        vibration element that applies a vibration to an orifice that        generates a fluid stream,    -   a control unit that controls a driving condition supplied to the        vibration element on the basis of a relative relationship        between a droplet discharged from the orifice and a satellite        droplet present between droplets, and    -   a sorting unit that sorts the droplet containing microparticles        on the basis of optical information detected from the        microparticles flowing through a flow path.

In the microparticle sorting device according to the present technology,the control unit may control the driving condition using absorptioneasiness indicating absorption easiness of the satellite droplet byeither preceding or subsequent droplet as an index.

In this case, the absorption easiness may be calculated on the basis ofa positional relationship between the satellite droplet and thepreceding and subsequent droplets.

Furthermore, the absorption easiness may also be calculated on the basisof a time from a break-off point of the fluid stream until the satellitedroplet is absorbed by either the preceding or subsequent droplet.

Moreover, the absorption easiness may also be calculated on the basis ofa distance from a break-off point of the fluid stream until thesatellite droplet is absorbed by either the preceding or subsequentdroplet.

In the microparticle sorting device according to the present technology,the driving condition controlled by the control unit may be a frequencyof the drive voltage.

In this case, the control unit may also control strength of the drivevoltage as the driving condition.

In the microparticle sorting device according to the present technology,the control unit may control the driving condition on the basis of apositional relationship between the orifice and a break-off point of thefluid stream.

Next, the present technology provides a microparticle sorting systemprovided with

-   -   a microparticle sorting device provided with    -   a voltage supply unit that supplies a drive voltage to a        vibration element that applies a vibration to an orifice that        generates a fluid stream, and    -   a sorting unit that sorts a droplet containing microparticles on        the basis of optical information detected from the        microparticles flowing through a flow path, and    -   a droplet control program that allows the microparticle sorting        device to execute a control function of controlling a driving        condition supplied to the vibration element that applies the        vibration to the orifice on the basis of a relative relationship        between the droplet discharged from the orifice that generates        the fluid stream and a satellite droplet present between        droplets.

Furthermore, provided is a microparticle sorting system provided with

-   -   a microparticle sorting device provided with    -   a voltage supply unit that supplies a drive voltage to a        vibration element that applies a vibration to an orifice that        generates a fluid stream, and    -   a sorting unit that sorts a droplet containing microparticles on        the basis of optical information detected from the        microparticles flowing through a flow path, and    -   a code of acquiring a droplet control program that allows the        microparticle sorting device to execute a control function of        controlling a driving condition supplied to the vibration        element that applies the vibration to the orifice on the basis        of a relative relationship between the droplet discharged from        the orifice that generates the fluid stream and a satellite        droplet present between droplets.

The present technology further provides a droplet sorting deviceprovided with

-   -   a voltage supply unit that supplies a drive voltage to a        vibration element that applies a vibration to an orifice that        generates a fluid stream, and    -   a sorting unit that sorts a droplet by controlling a driving        condition supplied to the vibration element on the basis of a        relative relationship between the droplet discharged from the        orifice and a satellite droplet present between droplets.

The present technology provides, in addition, a droplet control deviceprovided with a control unit that controls a driving condition suppliedto a vibration element that applies a vibration to an orifice on thebasis of a relative relationship between a droplet discharged from theorifice that generates a fluid stream and a satellite droplet presentbetween droplets, and a droplet control program that allows a dropletsorting device to execute a control function of controlling a drivingcondition supplied to a vibration element that applies a vibration to anorifice on the basis of a relative relationship between a dropletdischarged from the orifice that generates a fluid stream and asatellite droplet present between droplets.

In the present technology, “microparticles” broadly include bio-relatedmicroparticles such as cells, microorganisms, and liposomes, syntheticparticles such as latex particles, gel particles, and industrialparticles or the like.

The bio-related microparticles include chromosomes forming variouscells, liposomes, mitochondria, organelles (cell organelles) and thelike. The cells include animal cells (such as blood cells) and plantcells. The microorganisms include bacteria such as Escherichia coli,viruses such as tobacco mosaic virus, fungi such as yeast and the like.Moreover, the bio-related microparticles may also include bio-relatedpolymers such as nucleic acids, proteins, and complexes thereof.

Furthermore, the industrial particles may be, for example, an organic orinorganic polymer material, metal or the like. The organic polymermaterial includes polystyrene, styrene/divinylbenzene, polymethylmethacrylate and the like. The inorganic polymer material includesglass, silica, a magnetic material and the like. The metal includes goldcolloid, aluminum and the like. In general, shapes of the microparticlesare generally spherical, but they may be non-spherical, and its size,mass and the like are also not especially limited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic conceptual diagram schematically illustrating amicroparticle sorting device 1 of a first embodiment of the presenttechnology.

FIG. 2 is a schematic conceptual diagram schematically illustrating amicroparticle sorting device 1 of a second embodiment of the presenttechnology.

FIG. 3 is a view illustrating an example of a state of a fluid and adroplet discharged from an orifice P3.

FIG. 4 is a view illustrating an example of the state of the fluid andthe droplet discharged from the orifice P3, in which A illustrates astate in which a satellite droplet SD is absorbed by a preceding dropletD (fast), and B illustrates a state in which the satellite droplet SD isabsorbed by a subsequent droplet D (slow).

FIG. 5 is a view illustrating an example of the state of the fluid andthe droplet discharged from the orifice P3.

FIG. 6A is a view illustrating an example of the state of the fluid andthe droplet discharged from the orifice P3 before moving an imagingelement 151, and FIG. 6B is a view illustrating an example of the stateof the fluid and the droplet discharged from the orifice P3 after lowingthe imaging element 151.

FIG. 7 is a flowchart illustrating an example of a procedure ofcontrolling a frequency (clock value) of a drive voltage.

FIG. 8 is a flowchart illustrating an example of a procedure ofcontrolling the frequency (clock value) and strength (drive value) ofthe drive voltage.

FIG. 9 is a schematic conceptual diagram schematically illustrating afirst embodiment of a microparticle sorting system 2 according to thepresent technology.

FIG. 10 is a schematic conceptual diagram schematically illustrating asecond embodiment of a microparticle sorting system 2 according to thepresent technology.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred mode for carrying out the present technology isdescribed with reference to the drawings. An embodiment hereinafterdescribed illustrates an example of a representative embodiment of thepresent technology, and the scope of the present technology is notnarrowed by this. Note that, the description is given in the followingorder.

1. Microparticle sorting device 1

(1) Flow path P

(2) Light irradiation unit 11

(3) Light detection unit 12

(4) Vibration element V

(5) Voltage supply unit 13

(6) Sorting unit 14

(7) Droplet detection unit 15

(8) Control unit 16

(9) Analysis unit 17

(10) Storage unit 18

(11) Display unit 19

2. Microparticle sorting system 2

3. Droplet sorting device

4. Droplet control device

5. Droplet control program

<1. Microparticle Sorting Device>

A microparticle sorting device 1 according to the present technology isat least provided with a voltage supply unit 13, a control unit 16, anda sorting unit 14. Furthermore, this may also be provided with a flowpath P, a light irradiation unit 11, a light detection unit 12, avibration element V, a droplet detection unit 15, an analysis unit 17, astorage unit 18, a display unit 19 and the like as necessary.Hereinafter, each unit is described in detail in time series of sorting.

FIG. 1 is a schematic conceptual diagram schematically illustrating afirst embodiment of the microparticle sorting device 1 according to thepresent technology, and FIG. 2 is a schematic conceptual diagramschematically illustrating a second embodiment of the microparticlesorting device 1 according to the present technology.

(1) Flow path P

The microparticle sorting device 1 according to the present technologyis the device that sorts microparticles flowing through the flow path P.Although the microparticle sorting device 1 may be provided with theflow path P in advance, it is also possible to use a commerciallyavailable flow path P, a disposable tip provided with the flow path Pand the like.

A form of the flow path P is not especially limited, and may be freelydesigned. For example, this is not limited to the flow path P formed ina two-dimensional or three-dimensional substrate T of plastic (PP, PC,COP, PDMS and the like), glass and the like as in the first embodimentillustrated in FIG. 1, and the flow path P used in a conventional flowcytometer and the like may also be used in the microparticle sortingdevice 1 according to the present technology as in the second embodimentillustrated in FIG. 2.

Furthermore, a flow path width, a flow path depth, and a flow pathcross-sectional shape of the flow path P are not especially limited aslong as a laminar flow may be formed, and may be freely designed. Forexample, a micro flow path having the flow path width of 1 mm or smallermay also be used in the microparticle sorting device 1 according to thepresent technology. Especially, the micro flow path having the flow pathwidth of about 10 μm or larger and 1 mm or smaller is more preferablyused in the microparticle sorting device 1 according to the presenttechnology.

A sample inlet P1 to which a liquid (sample liquid) containing themicroparticles to be sorted is introduced, a sheath inlet P2 to which asheath liquid is introduced and the like are formed on the flow path P.In the first embodiment, the sample liquid is introduced from a sampleliquid storage unit B1 to the sample inlet P1, merged with the sheathliquid introduced from a sheath liquid storage unit B2 to the sheathinlet P2, and discharged from an orifice P3 provided at a terminal endof the flow path P.

Furthermore, although not illustrated, a suction outlet P4 for resolvingclogging or bubbles may be formed on the flow path P. A negativepressure source such as a vacuum pump is connected to the suction outletP4, and when the clogging or bubbles occur in the flow path P, apressure in the flow path P may be made a negative pressure totemporarily reverse the flow, thereby resolving the clogging or bubbles.

The microparticles allowed to flow through the flow path P may belabeled with one or two or more dyes such as fluorescent dyes. In thiscase, the fluorescent dyes available in the present technology include,for example, Cascade Blue, Pacific Blue, fluorescein isothiocyanate(FITC), phycoerythrin (PE), propidium iodide (PI), Texas Red (TR),peridinin chlorophyll protein (PerCP), allophycocyanin (APC),4′,6-diamidino-2-phenylindole (DAPI), Cy3, Cy5, Cy7, Brilliant Violet(BV421) and the like.

(2) Light irradiation unit 11

The microparticle sorting device 1 according to the present technologymay be provided with the light irradiation unit 11. The lightirradiation unit 11 irradiates the microparticles flowing through theflow path P with light. In the microparticle sorting device 1 accordingto the present technology, the light irradiation unit 11 is notindispensable, and it is also possible to irradiate the microparticlesflowing through the flow path P with light by using an external lightirradiation device and the like.

A type of the light applied from the light irradiation unit 11 is notespecially limited, but in order to surely generate fluorescence orscattered light from the microparticles, light having constant lightdirection, wavelength, and light intensity is desirable. There may be alaser, an LED and the like as an example. In a case of using the laser,a type thereof is not especially limited, and it is possible to freelycombine one or two or more of an argon ion (Ar) laser, a helium-neon(He—Ne) laser, a dye laser, a krypton (Cr) laser, a semiconductor laser,a solid-state laser obtained by combining the semiconductor laser and awavelength conversion optical element or the like to use.

The microparticle sorting device 1 according to the present technologymay also adopt so-called multi-spot to irradiate a plurality ofpositions of the flow path P with light. In this case, although notillustrated, a plurality of light irradiation units 11 may be provided,and although not illustrated, it is also possible to split light fromone light irradiation unit 11 via a light control unit such as aspectroscope to irradiate a plurality of positions of the flow path Pwith light.

(3) Light detection unit 12

The microparticle sorting device 1 according to the present technologymay be provided with the light detection unit 12. The light detectionunit 12 detects optical information emitted from the microparticlesflowing through the flow path P. In the microparticle sorting device 1according to the present technology, the light detection unit 12 is notindispensable, and it is also possible to detect the optical informationemitted from the microparticles flowing through the flow path P by usingan external light irradiation device and the like.

As long as the light detection unit 12 that may be used in themicroparticle sorting device 1 according to the present technology maydetect optical signals from the microparticles, a specific lightdetection method thereof is not especially limited, and it is possibleto freely select to adopt the light detection method used in thewell-known light detector. For example, it is possible to freely combineone or two or more of the light detection methods used in fluorescencemeasuring instrument, scattered light measuring instrument, transmittedlight measuring instrument, reflected light measuring instrument,diffracted light measuring instrument, ultraviolet spectroscopicmeasuring instrument, infrared spectroscopic measuring instrument, Ramanspectroscopic measuring instrument, FRET measuring instrument, FISHmeasuring instrument and other various spectrum measuring instruments, aPMT array or a photodiode array in which light receiving elements suchas PMTs and photodiodes are one-dimensionally arranged, those in which aplurality of independent detection channels such as two-dimensionallight receiving elements such as CCD or CMOS is arranged or the like toadopt.

The microparticle sorting device 1 according to the present technologymay also detect light from a plurality of positions of the flow path P.In this case, although not illustrated, a plurality of light detectionunits 12 may be provided, and although not illustrated, one lightdetection unit 12 may detect light from a plurality of positions of theflow path P by controlling optical paths of the light from a pluralityof positions of the flow path P via a light control unit such as amirror.

An installation site of the light detection unit 12 in the microparticlesorting device 1 according to the present technology is not especiallylimited as long as the optical signals from the microparticles may bedetected, and may be freely designed. For example, as in the first andsecond embodiments illustrated in FIGS. 1 and 2, this is preferablyarranged on a side opposite to the light irradiation unit 11 across theflow path P. This is because the light irradiation unit 11 and the lightdetection unit 12 may be arranged in a freer configuration by arrangingthe light detection unit 12 on the side opposite to the lightirradiation unit 11 across the flow path P. Furthermore, for example,since fluorescence is also radiated in a direction different from anincidence direction of the irradiation light, the light detection unit12 may also be arranged on the same side as the light irradiation unit11 or on a side at 90 degrees with reference to the flow path P.

(4) Vibration element V

The vibration element V vibrates the flow path P at a predeterminedfrequency to apply a minute vibration to the sheath liquid, and form adroplet of a fluid (sample liquid and sheath liquid) discharged from theorifice P3 to generate a fluid stream (droplet flow) S. The vibrationelement V is not especially limited and may be freely selected to beused according to a purpose. As an example, there may be a piezovibration element and the like.

Note that, it is sufficient that the vibration element V abuts the flowpath P; for example, this may be provided as an inner configuration ofthe substrate T provided with the flow path P, or provided as an innerconfiguration of the microparticle sorting device 1.

(5) Voltage supply unit 13

The voltage supply unit 13 supplies a drive voltage to the vibrationelement V. The drive voltage of the vibration element V is suppliedaccording to a sine wave in order to form a stable droplet, and iscontrolled by two parameters of frequency (clock value) and strength(drive value). A specific control method is described with the controlunit 16 described later.

(6) Sorting unit 14

The microparticle sorting device 1 according to the present technologymay further be provided with the sorting unit 14 that sorts themicroparticles. The sorting unit 14 sorts the microparticles on thebasis of data analyzed by the analysis unit 17 to be described laterfrom a value detected by the light detection unit 12. For example, thesorting unit 14 may sort the microparticles downstream the flow path Pon the basis of an analysis result such as a size, a form, and aninternal structure of the microparticles derived from analysis data.

More specifically, the droplet is generated from a discharge port of theflow path P by applying vibration to an entire flow path P or a partthereof by using the above-described vibration element V. Note that, itis possible to adjust a size of the droplet and generate the dropletcontaining a certain amount of microparticles by adjusting a liquidsending amount to the flow path P, a diameter of the discharge port, avibration frequency of the vibration element and the like.

Next, although not illustrated, a charge unit charges with a positive ornegative charge on the basis of the analysis result such as the size,form, and internal structure of the microparticles analyzed on the basisof the data analyzed by the analysis unit 17. The charge unit appliesthe positive or negative charge to the droplet discharged from theorifice P3, and includes a charging electrode, a voltage source forapplying a predetermined voltage to the charging electrode and the like.

The charging electrode may be arranged in contact with the sheath liquidand/or sample liquid flowing through the flow path to apply the chargeto the sheath liquid and/or sample liquid, and it is possible to providea charging electrode inlet on the substrate T provided with the flowpath P and insert the same into the charging electrode inlet, forexample. Note that, the charging electrode may be arranged in contactwith the sample liquid, arranged in contact with the sheath liquid, orarranged in contact with both the sample liquid and the sheath liquid.However, in consideration of an effect on cells to be sorted, it isdesirable that the charging electrode be arranged in contact with thesheath liquid.

By charging a desired droplet with the positive or negative charge tocharge the same in this manner, the droplet containing arbitrarymicroparticles may be separated by an electric force. Furthermore, bysynchronizing a timing of charging by the charge unit with the supplyvoltage to the vibration element V, it becomes possible to charge onlyan arbitrary droplet.

Then, the charged droplet a pathway of which is changed in a desireddirection by a polarizer plate 141 is sorted. Specifically, deflectionplates 141 a and 141 b that change a travel direction of each droplet inthe fluid stream S by an electric force acting between the same and thecharge applied to the droplet to guide the same to a predeterminedrecovery container are arranged so as to be opposed to each other acrossthe fluid stream S. As the deflection plates 141 a and 141 b, forexample, generally used electrodes may be used.

Positive or negative different voltages are applied to the deflectionplates 141 a and 141 b, and when the charged droplet passes through anelectric field formed by them, an electric force (Coulomb force) isgenerated, and each droplet is attracted in a direction toward eitherthe deflection plate 141 a or 141 b. In the microparticle sorting device1, it is possible to control a direction of a flow of the dropletsattracted by the electric field (side stream) by changing the polarityof the charge to the droplet and a charge amount, so that it becomespossible to simultaneously sort a plurality of particles different fromeach other.

Each droplet the pathway of which is changed in the desired direction bythe polarizer plates 141 a and 141 b is recovered by recovery containers142 a to 142 c. As the recovery containers 142 a to 142 c,general-purpose plastic tubes, glass tubes and the like may be used forexperiments. It is preferable that these recovery containers 142 a to142 c are arranged so as to be exchangeable in the device. Furthermore,a drainage passage of the recovered droplet may be connected to therecovery container that receives the particles not to be sorted out ofthe recovery containers 142 a to 142 c.

Note that, the number of recovery containers arranged in the dropletsorting device 1 is not especially limited. For example, in a case wheremore than three recovery containers are arranged, it is possible thateach droplet is guided to any one of the recovery containers dependingon the presence or absence of an electrical acting force between thesame and the deflection plates 141 a and 141 b and magnitude thereof.

(7) Droplet detection unit 15

The microparticle sorting device 1 according to the present technologymay be provided with the droplet detection unit 15. The dropletdetection unit 15 detects a state of a droplet D discharged from theorifice P3 of the flow path P and a satellite droplet SD present betweenthe droplets D. In the microparticle sorting device 1 according to thepresent technology, the droplet detection unit 15 is not indispensable,and it is also possible to detect the state of the droplet D dischargedfrom the orifice P3 of the flow path P and the satellite droplet SDbetween the droplets D by using an external detection device and thelike.

The droplet detection unit 15 may include an imaging element 151 thatimages the droplet D and the satellite droplet SD, a position adjustmentmechanism 152 for making a position of the imaging element 151 followfluctuation in break-off point BP, an image data processing unit 153that acquires position information of the droplet D and the satellitedroplet SD from an imaged image and the like. As the imaging element151, various imaging elements such as a photoelectric conversion elementmay be used in addition to an imaging device such as a CCD or CMOScamera. Note that, the microparticle sorting device 1 of this embodimentmay also be provided with a light source (not illustrated) thatilluminates an imaging region in addition to the imaging element 151.

The image data processing unit 153 may also include an informationprocessing device including, for example, a general-purpose processor, amain storage device, an auxiliary storage device and the like. In thiscase, it is possible to acquire the position information of thesatellite droplet by inputting image data indicating the state of thedroplet and the satellite droplet imaged by the imaging element 151 tothe image data processing unit 153 and executing a programmed controlalgorithm. Such a computer program may be stored in a recording mediumsuch as a magnetic disk, an optical disk, a magneto-optical disk, and aflash memory, for example, or may be distributed via a network.

(8) Control unit 16

The control unit 16 controls a driving condition supplied to thevibration element V on the basis of a relative relationship between thedroplet D discharged from the orifice P3 and the satellite droplet SDpresent between the droplets D. Specifically, the control unit 16controls the frequency (clock value) and/or strength (drive value) ofthe drive voltage supplied to the vibration element V. The control unit16 may include an information processing device and the like including,for example, a general-purpose processor, a main storage device, anauxiliary storage device and the like.

In that case, it is possible to automatically control the frequency(clock value) and/or strength (drive value) of the drive voltagesupplied from the voltage supply unit 13 to the vibration element V byinputting the information of the droplet D and the satellite droplet SDacquired by the image data processing unit 153 of the droplet detectionunit 15 to the control unit 16 and executing the programmed controlalgorithm. Such a computer program may be stored in a recording mediumsuch as a magnetic disk, an optical disk, a magneto-optical disk, and aflash memory, for example, or may be distributed via a network.

Hereinafter, the control method performed by the control unit 16 isdescribed in detail.

Generally, the following is known in droplet formation.

(1) The closer the break-off point BP is to the orifice P3, the moreadvantageous it is for sorting.

(2) For the sorting, a state in which the satellite droplet SD isabsorbed by a preceding droplet D (fast) or a state in which this isabsorbed by a subsequent droplet D (slow) is suitable.

(3) In a case where the satellite droplet SD is not absorbed by thepreceding or subsequent droplet D, the side stream might becomeunstable.

(4) A state in which a vibration transmission characteristic isexcellent and the break-off point BP changes according to a change indrive value may respond to an environmental change such as temperaturechange during the sorting.

(5) For the sorting, a state in which the droplet is bilaterallysymmetrical is suitable.

(6) In a cell sorter with a fixed flow cell (refer to, for example, FIG.2), a frequency satisfying (1) to (5) described above is adjusted inadvance at the time of device installation, and it is not necessary toadjust the frequency again when a user uses the same. However, in a cellsorter in which the flow path may be exchanged (for example, tipexchange type illustrated in FIG. 1), the frequency satisfying (1) to(5) described above slightly differs for each flow path, so that it isdesirable to adjust the frequency to determine an optimum frequency foreach flow path each time the flow path is exchanged.

Therefore, the microparticle sorting device 1 according to the presenttechnology determines the driving condition of the vibration element Vfor forming the droplet satisfying (1) to (5) described above, that is,the frequency (clock value) and/or strength (drive value) of the drivevoltage of the vibration element V by a method such as image processing.Specifically, the microparticle sorting device 1 according to thepresent technology may control the driving condition by using, as anindex, absorption easiness indicating absorption easiness of thesatellite droplet SD by either the preceding or subsequent droplet D,for example, as the control method of the frequency (clock value) and/orstrength (drive value) of the drive voltage of the vibration element Vby the control unit 16. By using the absorption easiness as the index,even in a case where the position of the satellite droplet SD fluctuatesdue to the environmental change such as the temperature change duringthe sorting, the state in which the satellite droplet SD is absorbed bythe preceding or subsequent droplet D may be maintained to continuestable sorting.

Note that, there are several possible methods for determining whether atarget droplet is the droplet D or the satellite droplet SD, and themethod is not especially limited; a method using an area value afterbinarization of the target droplet and a method using also a width ofthe target droplet may be applied, for example. In the method using thearea value, for example, it is determined to be the droplet D in a casewhere the area value is X or larger, and it is determined to be thesatellite droplet SD in a case where the area value is smaller than X.In the method using the width, for example, the largest value of thewidth is acquired out of a plurality of target droplets, and it isdetermined to be the droplet D in a case where the width is not smallerthan half the same, and it is determined to be the satellite droplet SDin a case where the width is smaller than the same. Furthermore, it isalso possible to determine by combining these two determination methods.

Note that, in a case where the satellite SD is continuous to the dropletD but a satellite portion may be clearly detected as illustrated in FIG.3, it is also possible to calculate the absorption easiness describedabove by detecting a constricted part (width inflection point) of thesatellite portion and separating the satellite portion from the dropletD (refer to broken line in FIG. 3).

Furthermore, in contrast, it is possible to determine whether or not thesatellite droplet SD is absorbed by the droplet D by whether or not thesatellite droplet SD is present below the droplet D. For example, in acase where two objects are continuously determined to be the droplets D,it may be determined that the satellite droplet SD is absorbed. Notethat, in order to avoid erroneous determination, the satelliteabsorption may be determined in a case where three objects arecontinuously determined to be the droplets.

In a case where it is determined that the satellite droplet SD isabsorbed, it is also possible to specify whether it is in the state inwhich the satellite droplet SD is absorbed by the preceding droplet D(fast) or in the state in which this is absorbed by the subsequentdroplet D (slow) depending on the position of the satellite droplet SDdetected the last. It is also possible to limit the case where it isdetermined that the satellite droplet SD is absorbed to only either thefast or slow state, for example, by utilizing this. Therefore, thesorting may always be performed under a constant droplet condition.

[Calculation Method Example 1 of Absorption Easiness]

The absorption easiness may be calculated on the basis of, for example,a positional relationship between the satellite droplet SD and thepreceding and subsequent droplets D. A specific example is describedwith reference to FIG. 4. FIG. 4 is a view illustrating a state of thefluid and the droplet discharged from the orifice P3, in which Aillustrates a state in which the satellite droplet SD is absorbed by thepreceding droplet D (fast), and B illustrates a state in which thesatellite droplet SD is absorbed by the subsequent droplet D (slow).

First, absorption easiness satellite absorption degree may be calculatedon the basis of following calculation expression (1) or (2), forexample, on the basis of a gravity center position Y1 of a specificsatellite droplet SD (in the example illustrated in FIG. 4, a secondsatellite droplet 2ndSD is selected) and gravity center positions Y0 andY2 of the preceding and subsequent droplets D (in the exampleillustrated in FIG. 4, a first droplet 1stD and a second droplet 2ndD).

[In case of state in which satellite droplet SD is absorbed by precedingdroplet D (fast)]

Absorption easiness=(Y1−Y0)/(Y2−Y0)  (1)

[In case of state in which satellite droplet SD is absorbed bysubsequent droplet D (slow)]

Absorption easiness=(Y2−Y1)/(Y2−Y0)  (2)

In this case, a case where the absorption easiness is further closer to1 is considered to be a state in which the absorption easiness by thedroplet D is high, and this may be used as the index.

The satellite droplet used for calculating the absorption easiness isconsidered to be a first droplet 1stD (the satellite droplet immediatelysubsequent to the droplet immediately preceding the break-off: lastattached droplet), a second satellite droplet 2ndSD, a third satellitedroplet 3rdSD (refer to FIG. 4) and the like, and by using the satellitedroplet SD on a lower side, the index is more reliable for observing theabsorption easiness of the satellite droplet. However, in this case,depending on an angle of view of the imaging element 151 of the dropletdetection unit 15 described above, it might be necessary to move theimaging element 151, and there is a risk for an increase in adjustingtime. It should determine the satellite droplet SD to be used from theangle of view of the imaging element 151, tendency of an actualabsorption position of the satellite droplet SD and the like.

Note that, in a case where a relevant satellite droplet SD is alreadyabsorbed by the droplet and is not present as illustrated in FIG. 5, itis possible to determine a satellite droplet absorbing direction (fastor slow) from the position of the satellite droplet SD above the same;however, since the second satellite is already absorbed, the absorptioneasiness is 1.

[Calculation method example 2 of absorption easiness]

The absorption easiness may be calculated on the basis of, for example,a time from the break-off point BP of the fluid stream until thesatellite droplet SD is absorbed by either the preceding or subsequentdroplet D. For example, in FIG. 4A, it is present up to the thirdsatellite droplet 3rdSD, but a fourth satellite droplet is not present,so that it is considered that this is absorbed by a fourth droplet 4thD.The time from the break-off point BP until the satellite droplet SD isabsorbed is calculated from an imaging time of the break-off point BPand an imaging time of the fourth droplet 4thD, and this may be used asthe index considering that the shorter the time is, the higher theabsorption easiness is.

Note that, although the time from the break-off point BP until thesatellite droplet SD is absorbed is made the index in the calculationmethod example 2, it is also possible to simply make it the index towhat number of droplet D this is absorbed. For example, in FIG. 5, sincethe second satellite 2ndSD is not present, it is considered that this isabsorbed by the second droplet 2ndD, so that it is possible to determinethat the absorption easiness is higher than that in a case in FIG. 4A inwhich this is considered to be absorbed by the fourth droplet 4thD.

[Calculation method example 3 of absorption easiness]

The absorption easiness may also be calculated on the basis of, forexample, a distance from the break-off point BP of the fluid streamuntil the satellite droplet SD is absorbed by either the preceding orsubsequent droplet D. For example, as compared with the case in FIG. 4Ain which this is considered to be absorbed by the fourth droplet 4thD,the distance from the break-off point BP is shorter in FIG. 5 in whichthis is considered to be absorbed by the second droplet 2ndD, so that itis considered to be in a state in which the absorption easiness ishigher, and this may be made the index.

Using the absorption easiness described above as the index, the optimumfrequency (clock value) and/or optimum strength (drive value) isdetermined by repeating while changing the frequency (clock value)and/or strength (drive value) of the drive voltage. At that time, thechange in frequency (clock value) of the drive voltage is not especiallylimited, but in a case where a diameter of the orifice P3 is 70 μm, itmay be carried out within a range of 49 kHz±3 kHz in increment of 0.1kHz, for example.

Furthermore, when determining the optimum frequency (clock value) and/orstrength (drive value), the positional relationship between the orificeP3 and the break-off point BP may be taken into consideration.Specifically, as illustrated in FIG. 6, a process of adjusting theposition of the break-off point BP in a break-off range set in advance(refer to broken line square in FIG. 6) is repeatedly performed whilechanging the frequency (clock value) and/or strength (drive value).

A method thereof is not especially limited, and, for example, there is amethod of adjusting the position of the break-off point BP bysequentially performing a process of moving the imaging element 151 ofthe above-described droplet detection unit 15 by a certain distance andchecking the position of the break-off point BP by image processing. Incontrast, there also is a method of acquiring a correlation valuebetween the number of pixels of the droplet image and a sensor amount ofthe imaging element 151 in advance, calculating a target sensor valuefrom a pixel distance between the break-off point BP and the break-offrange, and moving the imaging element 151 so as to reach the sensorvalue. In this method, the number of times of movement of the imagingelement 151 for position adjustment may be reduced, so that it ispossible to efficiently adjust the position.

Then, the frequency (clock value) and/or strength (drive value) isranked in descending order of the height of the break-off point BP, itis sequentially determined while using the absorption easiness of thesatellite droplet SD as the index from the frequency (clock value)and/or strength (drive value) with the higher break-off point BP, andthe frequency (clock value) and/or strength (drive value) with higherabsorption easiness is determined as the optimum frequency (clock value)and/or strength (drive value). This makes it possible to moreefficiently adjust the optimum frequency (clock value) and/or optimumstrength (drive value).

In this manner, it is possible to more efficiently control the drivingcondition by determining the optimum frequency (clock value) and/oroptimum strength (drive value) by combining the determination of thefrequency (clock value) and/or strength (drive value) by the break-offpoint BP and determination of the frequency (clock value) and/orstrength (drive value) using the absorption easiness as the index.

As described above in detail, the microparticle sorting device 1according to the present technology may stably form the droplet D evenwhen there is the environmental fluctuation. Therefore, in the tipexchange type cell sorter, the optimum frequency (clock value) and/orstrength (drive value) may be determined for each tip, and droplet shapecontrol of high stability and robustness may be realized.

Furthermore, the microparticle sorting device 1 according to the presenttechnology may determine the optimum frequency (clock value) and/orstrength (drive value) for forming the stable side stream and mayrealize stable sorting. As a result, according to the microparticlesorting device 1 according to the present technology, it becomespossible to realize highly accurate and stable sorting for a long periodof time while suppressing an effect by a change in environmentaltemperature, reduction of sheath liquid/sample liquid, clogging andmixing of bubbles, and a change in droplet shape.

Hereinafter, a specific procedure of the control method performed by thecontrol unit 16 of the microparticle sorting device 1 according to thepresent technology is described with reference to a flowchart.

[Example of controlling frequency (clock value) of drive voltage]

FIG. 7 is a flowchart illustrating an example of a procedure ofcontrolling the frequency (clock value) of the drive voltage. First, thefrequency (clock value) of the drive voltage is set to an arbitraryfrequency (clock value) (step S1). Next, the control unit 16 acquiresthe droplet image including the break-off point BP (step S2). Then, thecontrol unit 16 calculates the absorption easiness of the satellitedroplet SD by the droplet D on the basis of the above-describedcalculation method of the absorption easiness (step S3).

The control unit 16 iteratively executes an iterative processcorresponding to steps S1 to S3 illustrated in FIG. 7 by N times equalto the number of data to be ranked. When the iterative process isfinished, the procedure shifts to step S4.

At steps S4 and S5, the control unit 16 selects and ranks thefrequencies on the basis of the calculated absorption easiness, and setsthe optimum frequency with the highest absorption easiness. Note that,in a case where there are the frequencies with the same absorptioneasiness, it is possible to appropriately set a rule; for example, in acase of the calculation method example 1, the absorption easiness forthe upper satellite droplet SD is used, or a higher frequency isselected. Furthermore, since sorting efficiency is improved at a higherfrequency in general, the optimum frequency may be selected by combiningthe absorption easiness and the frequency value.

Thereafter, in order to stabilize the side stream, the strength (drivevalue) of the drive voltage is finely adjusted (step S6), and in a casewhere it is determined that the condition is not suitable for thesorting such as when a side stream splash is observed in the course ofthe fine adjustment, after the procedure is returned to step S5 toselect a defective frequency condition, the strength (drive value) ofthe drive voltage is finely adjusted again (step S6), the frequency atwhich the side stream is stabilized is finally determined (step S7), andthe control procedure is finished.

[Example of controlling frequency (clock value) and strength (drivevalue) of drive voltage]

FIG. 8 is a flowchart illustrating an example of a procedure ofcontrolling the frequency (clock value) and strength (drive value) ofthe drive voltage. First, the strength (drive value) of the drivevoltage and the frequency (clock value) of the drive voltage are set toan arbitrary frequency (clock value) (steps S1 and S2). Next, thecontrol unit 16 acquires the droplet image including the break-off pointBP (step S3). Then, the control unit 16 calculates the absorptioneasiness of the satellite droplet SD by the droplet D on the basis ofthe above-described calculation method of the absorption easiness (stepS4).

The control unit 16 iteratively executes an iterative processcorresponding to steps S1 to S4 illustrated in FIG. 8 by N times(frequency) and M times (strength) equal to the number of data to beranked. When the iterative process is finished, the procedure shifts tostep S5.

At steps S5 and S6, the control unit 16 selects and ranks thefrequencies and strengths on the basis of the calculated absorptioneasiness, and sets the optimum frequency and optimum strength with thehighest absorption easiness. This makes it possible to simultaneouslydetermine the optimum frequency and strength.

Note that, in a case where there are the frequencies with the sameabsorption easiness, it is possible to appropriately set a rule; forexample, in a case of the calculation method example 1, the absorptioneasiness for the upper satellite droplet SD is used, or a higherfrequency is selected. Furthermore, since sorting efficiency is improvedat a higher frequency in general, the optimum frequency may be selectedby combining the absorption easiness and the frequency value.

Furthermore, in a case where there are the strengths having the sameabsorption easiness, it is possible to appropriately set a rule; forexample, a low vibration strength condition is given priority in orderto secure a vibration strength margin.

Thereafter, in order to stabilize the side stream, the strength (drivevalue) of the drive voltage is finely adjusted (step S7), and in a casewhere it is determined that the condition is not suitable for thesorting such as when a side stream splash is observed in the course ofthe fine adjustment, after the procedure is returned to step S6 toselect a defective frequency condition, the strength (drive value) ofthe drive voltage is finely adjusted again (step S7), the frequency andstrength at which the side stream is stabilized are finally determined(step S8), and the control procedure is finished.

(9) Analysis unit 17

The microparticle sorting device 1 according to the present technologymay further be provided with the analysis unit 17 as necessary. Theanalysis unit 17 is connected to the light detection unit 12 andanalyzes the optical information detected from the microparticles by thelight detection unit 12.

For example, the analysis unit 17 calculates a feature amount of eachmicroparticle from the optical information of light received from thelight detection unit 12. Specifically, the feature amount indicating thesize, form, internal structure and the like of the microparticles iscalculated from detected values of received fluorescence and scatteredlight.

Note that, the analysis unit 17 is not indispensable in themicroparticle sorting device 1 according to the present technology, andit is also possible to analyze the state and the like of themicroparticles by using an external analysis device and the like on thebasis of the optical information detected by the light detection unit12. For example, the analysis unit 17 may be implemented by a personalcomputer or a CPU, and may be stored as a program in a hardware resourceprovided with a recording medium (for example, a non-volatile memory(USB memory), an HDD, a CD and the like) and the like and allowed tofunction by the personal computer or CPU. Furthermore, the analysis unit17 may be connected to each unit of the microparticle sorting device 1via a network.

(10) Storage unit 18

The microparticle sorting device 1 according to the present technologymay further be provided with the storage unit 18 in which various piecesof information are stored. The storage unit 18 may store any itemregarding the sorting of the microparticles such as information datadetected by each of the light detection units 12, information datadetected by the droplet detection unit 15, control data by the controlunit 16, analysis data generated by the analysis unit 17, and data ofthe microparticles sorted by the sorting unit 14.

In the microparticle sorting device 1 according to the presenttechnology, the storage unit 18 is not indispensable, and an externalstorage device may also be connected. As the storage unit 18, forexample, a hard disk and the like may be used.

(11) Display unit 19

The microparticle sorting device 1 according to the present technologymay be provided with the display unit 19 that displays various types ofinformation. The display unit 19 may display any item regarding thesorting of the microparticles such as information data detected by eachof the light detection units 12, information data detected by thedroplet detection unit 15, control data by each control unit, analysisdata generated by the analysis unit 17, and data of the microparticlessorted by the sorting unit 14.

In the microparticle sorting device 1 according to the presenttechnology, the display unit 19 is not indispensable, and an externaldisplay device may also be connected. As the display unit 19, forexample, a display, a printer and the like may be used.

<2. Microparticle sorting system 2>

FIG. 9 is a schematic conceptual diagram schematically illustrating afirst embodiment of a microparticle sorting system 2 according to thepresent technology, and FIG. 10 is a schematic conceptual diagramschematically illustrating a second embodiment of the microparticlesorting system 2 according to the present technology. The microparticlesorting system 2 according to the first embodiment includes amicroparticle sorting device 21 provided with a voltage supply unit 13and a sorting unit 14, and a droplet control program 22.

The droplet control program 22 of the microparticle sorting system 2according to the present technology is the program that allows themicroparticle sorting device 21 to execute a function similar to thecontrol function performed by the control unit 16 of the microparticlesorting device 1 described above, provided in a state of being stored ina recording medium such as a magnetic disk, an optical disk, amagneto-optical disk, or a flash memory, for example, and is downloadedto an electronic computer C and the like to be used.

Alternatively, the droplet control program 22 externally distributed viaa network such as the Internet may be downloaded to the electroniccomputer C and the like to be used. In this case, the microparticlesorting system 2 may be provided in a state in which the microparticlesorting device 21 and a code 23 of acquiring the droplet control program21 are packaged as in the second embodiment illustrated in FIG. 10.

The electronic computer C to which the droplet control program 22 isdownloaded acquires a relative relationship between a droplet Ddischarged from an orifice P3 and a satellite droplet SD present betweenthe droplets D, a control algorithm of the downloaded droplet controlprogram 22 is executed, and a driving condition supplied to a vibrationelement V is calculated. The electronic computer C issues an instructionto the microparticle sorting device 21 on the basis of the calculateddriving condition, so that the driving condition of the drive voltagesupplied from the voltage supply unit 13 of the microparticle sortingdevice 21 to the vibration element V is automatically controlled.

Note that, the microparticle sorting system 2 may also be provided witha flow path P, a light irradiation unit 11, a light detection unit 12, avibration element V, a droplet detection unit 15, an analysis unit 17, astorage unit 18, a display unit 19 and the like as necessary. They maybe provided in the microparticle sorting device 21, or may be arrangedindependently. For example, although the microparticle sorting device 21may be provided with the flow path P in advance, it is also possible toinstall a commercially available flow path P, a disposable tip providedwith the flow path P and the like in the microparticle sorting device 21to analyze or sort. Furthermore, although the light irradiation unit 11and the light detection unit 12 may be provided on the microparticlesorting device 21 in advance, it is also possible to irradiatemicroparticles flowing through the flow path P with light or detectlight from the microparticles by using external light irradiationdevice, light detection device and the like. Moreover, the dropletdetection unit 15, the analysis unit 17, the storage unit 18, thedisplay unit 19 and the like may be provided in the microparticlesorting device 21 in advance, but external detection device, analysisdevice, storage device, display device and the like may also be used. Inthis case, each device may be connected to each other via a network.

Note that, since the details of each unit are the same as the details ofeach unit of the microparticle sorting device 1 according to the presenttechnology described above, the description thereof is herein omitted.

<3. Droplet sorting device>

A droplet sorting device according to the present technology is at leastprovided with a voltage supply unit and a sorting unit that sorts adroplet. That is, the above-described microparticle sorting device 1 mayalso be used as the droplet sorting device that sorts the droplet notcontaining microparticles.

Note that, the droplet sorting device according to the presenttechnology may also be provided with a flow path, a light irradiationunit, a light detection unit, a vibration element, a droplet detectionunit, an analysis unit, a control unit, a storage unit, a display unitand the like as necessary. Since the details of each unit are the sameas the details of each unit of the microparticle sorting device 1according to the present technology described above, the descriptionthereof is herein omitted.

<4. Droplet control device>

A droplet control device according to the present technology is at leastprovided with a control unit similar to the control unit 16 of themicroparticle sorting device 1 described above; that is, the controlunit 16 of the microparticle sorting device 1 described above may alsobe used independently as a droplet control device.

Note that, since the details of the control unit of the droplet controldevice is the same as that of the control unit 16 of the microparticlesorting device 1 described above, the description thereof is hereinomitted.

<5. Droplet control program>

A droplet control program according to the present technology is theprogram that allows the microparticle sorting device 21 to execute afunction similar to the control function performed by the control unit16 of the microparticle sorting device 1 described above. That is, thedroplet control program 22 of the microparticle sorting system 2described above may also be independently distributed as the dropletcontrol program.

Note that, since the details of the control function are the same as thecontrol function performed by the control unit 16 of the microparticlesorting device 1 described above, the description thereof is hereinomitted.

Note that, the present technology may also have the followingconfiguration.

(1)

A microparticle sorting device provided with:

a voltage supply unit that supplies a drive voltage to a vibrationelement that applies a vibration to an orifice that generates a fluidstream;

a control unit that controls a driving condition supplied to thevibration element on the basis of a relative relationship between adroplet discharged from the orifice and a satellite droplet presentbetween droplets; and

a sorting unit that sorts the droplet containing microparticles on thebasis of optical information detected from the microparticles flowingthrough a flow path.

(2)

The microparticle sorting device according to (1), in which the controlunit controls the driving condition using absorption easiness indicatingabsorption easiness of the satellite droplet by either preceding orsubsequent droplet as an index.

(3)

The microparticle sorting device according to (2), in which theabsorption easiness is calculated on the basis of a positionalrelationship between the satellite droplet and the preceding andsubsequent droplets.

(4)

The microparticle sorting device according to (2) or (3), in which theabsorption easiness is calculated on the basis of a time from abreak-off point of the fluid stream until the satellite droplet isabsorbed by either the preceding or subsequent droplet.

(5)

The microparticle sorting device according to any one of (2) to (4), inwhich the absorption easiness is calculated on the basis of a distancefrom a break-off point of the fluid stream until the satellite dropletis absorbed by either the preceding or subsequent droplet.

(6)

The microparticle sorting device according to any one of (1) to (5), inwhich the driving condition is a frequency of the drive voltage.

(7)

The microparticle sorting device according to (6), in which the drivingcondition is strength of the drive voltage.

(8)

The microparticle sorting device according to any one of (1) to (7), inwhich the control unit controls the driving condition on the basis of apositional relationship between the orifice and a break-off point of thefluid stream.

(9)

A microparticle sorting system provided with:

a microparticle sorting device provided with

a voltage supply unit that supplies a drive voltage to a vibrationelement that applies a vibration to an orifice that generates a fluidstream, and

a sorting unit that sorts a droplet containing microparticles on thebasis of optical information detected from the microparticles flowingthrough a flow path; and

a droplet control program that allows a droplet sorting device toexecute a control function of controlling a driving condition suppliedto the vibration element that applies the vibration to the orifice onthe basis of a relative relationship between the droplet discharged fromthe orifice that generates the fluid stream and a satellite dropletpresent between droplets.

(10)

A microparticle sorting system provided with:

a microparticle sorting device provided with

a voltage supply unit that supplies a drive voltage to a vibrationelement that applies a vibration to an orifice that generates a fluidstream, and

a sorting unit that sorts a droplet containing microparticles on thebasis of optical information detected from the microparticles flowingthrough a flow path; and

a code of acquiring a droplet control program that allows a dropletsorting device to execute a control function of controlling a drivingcondition supplied to the vibration element that applies the vibrationto the orifice on the basis of a relative relationship between thedroplet discharged from the orifice that generates the fluid stream anda satellite droplet present between droplets.

(11)

A droplet sorting device provided with:

a voltage supply unit that supplies a drive voltage to a vibrationelement that applies a vibration to an orifice that generates a fluidstream; and

a sorting unit that sorts a droplet by controlling a driving conditionsupplied to the vibration element on the basis of a relativerelationship between the droplet discharged from the orifice and asatellite droplet present between droplets.

(12)

A droplet control device provided with: a control unit that controls adriving condition supplied to a vibration element that applies avibration to an orifice on the basis of a relative relationship betweena droplet discharged from the orifice that generates a fluid stream anda satellite droplet present between droplets.

(13)

A droplet control program, that allows a droplet sorting device toexecute a control function of controlling a driving condition suppliedto a vibration element that applies a vibration to an orifice on thebasis of a relative relationship between a droplet discharged from theorifice that generates a fluid stream and a satellite droplet presentbetween droplets.

Note that, the effect described in this specification is illustrativeonly; the effect is not limited thereto and there may also be anothereffect.

REFERENCE SIGNS LIST

-   1 Microparticle sorting device-   P Flow path-   P1 Sample inlet-   P2 Sheath inlet-   P3 Orifice-   11 Light irradiation unit-   12 Light detection unit-   V Vibration element-   13 Voltage supply unit-   14 Sorting unit-   141 a, 141 b Deflection plate-   142 a to 142 c Recovery container-   15 Droplet detection unit-   151 Imaging element-   152 Position adjustment mechanism-   153 Image data processing unit-   BP Break-off point-   16 Control unit-   D Droplet-   SD Satellite droplet-   17 Analysis unit-   18 Storage unit-   19 Display unit-   2 Microparticle sorting system-   22 Droplet control program-   23 Code

1. A microparticle sorting device comprising: a voltage supply unit thatsupplies a drive voltage to a vibration element that applies a vibrationto an orifice that generates a fluid stream; a control unit thatcontrols a driving condition supplied to the vibration element on abasis of a relative relationship between a droplet discharged from theorifice and a satellite droplet present between droplets; and a sortingunit that sorts the droplet containing microparticles on a basis ofoptical information detected from the microparticles flowing through aflow path.
 2. The microparticle sorting device according to claim 1,wherein the control unit controls the driving condition using absorptioneasiness indicating absorption easiness of the satellite droplet byeither preceding or subsequent droplet as an index.
 3. The microparticlesorting device according to claim 2, wherein the absorption easiness iscalculated on a basis of a positional relationship between the satellitedroplet and the preceding and subsequent droplets.
 4. The microparticlesorting device according to claim 2, wherein the absorption easiness iscalculated on a basis of a time from a break-off point of the fluidstream until the satellite droplet is absorbed by either the precedingor subsequent droplet.
 5. The microparticle sorting device according toclaim 2, wherein the absorption easiness is calculated on a basis of adistance from a break-off point of the fluid stream until the satellitedroplet is absorbed by either the preceding or subsequent droplet. 6.The microparticle sorting device according to claim 1, wherein thedriving condition is a frequency of the drive voltage.
 7. Themicroparticle sorting device according to claim 6, wherein the drivingcondition is strength of the drive voltage.
 8. The microparticle sortingdevice according to claim 1, wherein the control unit controls thedriving condition on a basis of a positional relationship between theorifice and a break-off point of the fluid stream.
 9. A microparticlesorting system comprising: a microparticle sorting device provided witha voltage supply unit that supplies a drive voltage to a vibrationelement that applies a vibration to an orifice that generates a fluidstream, and a sorting unit that sorts a droplet containingmicroparticles on a basis of optical information detected from themicroparticles flowing through a flow path; and a droplet controlprogram that allows the microparticle sorting device to execute acontrol function of controlling a driving condition supplied to thevibration element that applies the vibration to the orifice on a basisof a relative relationship between the droplet discharged from theorifice that generates the fluid stream and a satellite droplet presentbetween droplets.
 10. A microparticle sorting system comprising: amicroparticle sorting device provided with a voltage supply unit thatsupplies a drive voltage to a vibration element that applies a vibrationto an orifice that generates a fluid stream, and a sorting unit thatsorts a droplet containing microparticles on a basis of opticalinformation detected from the microparticles flowing through a flowpath; and a code of acquiring a droplet control program that allows themicroparticle sorting device to execute a control function ofcontrolling a driving condition supplied to the vibration element thatapplies the vibration to the orifice on a basis of a relativerelationship between the droplet discharged from the orifice thatgenerates the fluid stream and a satellite droplet present betweendroplets.
 11. A droplet sorting device comprising: a voltage supply unitthat supplies a drive voltage to a vibration element that applies avibration to an orifice that generates a fluid stream; and a sortingunit that sorts a droplet by controlling a driving condition supplied tothe vibration element on a basis of a relative relationship between thedroplet discharged from the orifice and a satellite droplet presentbetween droplets.
 12. A droplet control device comprising: a controlunit that controls a driving condition supplied to a vibration elementthat applies a vibration to an orifice on a basis of a relativerelationship between a droplet discharged from the orifice thatgenerates a fluid stream and a satellite droplet present betweendroplets.
 13. A droplet control program, that allows a droplet sortingdevice to execute a control function of controlling a driving conditionsupplied to a vibration element that applies a vibration to an orificeon a basis of a relative relationship between a droplet discharged fromthe orifice that generates a fluid stream and a satellite dropletpresent between droplets.